Construction of a Pt-modified chestnut-shell-like ZnO photocatalyst for high-efficiency photochemical water splitting

Abstract

Super-slenderness-ratio, chestnut-shell-like ZnO, ZnO flowers, ZnO nanorods (NRs), and ZnO nanoparticles (NPs) were synthesized as photocatalysts using a facile hydrothermal method. To enhance its photocatalytic H2 production rates, Pt serving as a co-catalyst was loaded onto the surface of ZnO to form a Schottky heterostructure. A series of different Pt-modified chestnut-shell-like ZnO, ZnO flowers, ZnO NRs and ZnO NPs were prepared, and their photochemical water-splitting ability was investigated in detail. X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy results confirmed that approximately 5–10-nm-diameter Pt NPs were well dispersed on three-dimensional (3D) chestnut-shell-like ZnO, ZnO flowers, ZnO NRs, and ZnO NPs matrixes to form a Pt/ZnO heterojunction. Low-band-gap energies (minimum value 2.83 eV) and low electron-hole recombination rates were confirmed by ultraviolet–visible diffuse reflectance spectra and photoluminescence spectra, respectively, which demonstrated that the Pt-modified 3D chestnut-shell-like ZnO composites have excellent photochemical properties. The time-course I-t cycles and photocatalytic H2 production rate cycle measurements for the photocatalyst confirmed that the photochemical performance of Pt-modified ZnO nanocomposite have superstability and altitudinal reusability. The photochemical water-splitting results confirmed that the optimal sample was 4-wt.%-Pt-modified ZnO composites, the H2 production rate of which was approximately1.97 mmol h−1 g−1, which was approximately 4, 2.7, 3.2, and 5.8 times that of pristine chestnut-shell-like ZnO, 4-wt.%-Pt modified ZnO flowers, ZnO NRs, and ZnO NPs, respectively. This indicated that 4-wt.%-Pt-modified chestnut-shell-like ZnO exhibits excellent photocatalytic performance.